Research continues in which the human electroretinogram and the visual evoked potential are recorded in response to alternating stimuli. Responses are recorded which result from stimulation of the peripheral retina as well as of the central regions. The methods may be used to obtain scotopic as well as photopic potentials, and current experiments are concerned with the Purkinje shift, the luminance-duration relation and the effects of the alpha rhythm on the VECP. Other stimulus variables are under examination including those of spatial frequency, movement, and color adaptation. An additivity model accounts for most current results. BIBLIOGRAPHIC REFERENCES: Armington, John C., Spectral Sensitivity of Low Level Electroretinograms, Vision Research, 1976, vol. 16, 31-35. Korth, Matthias, and Armington, John C.; Stimulus Alternation and the Purkinje Shift, Vision Research, 1976 (in press).